Improve QueryMatcher TypeScript definition (#7555)

src/@types/common.ts

@@ -23,3 +23,14 @@ export type Writeable<T> = { -readonly [P in keyof T]: T[P] };
 
 export type ComponentClass = keyof JSX.IntrinsicElements | JSXElementConstructor<any>;
 export type ReactAnyComponent = React.Component | React.ExoticComponent;
+
+// Based on https://stackoverflow.com/a/58436959
+type Join<K, P> = K extends string | number ?
+    P extends string | number ?
+        `${K}${"" extends P ? "" : "."}${P}`
+        : never : never;
+
+type Prev = [never, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ...0[]];
+
+export type Leaves<T, D extends number = 5> = [D] extends [never] ? never : T extends object ?
+    { [K in keyof T]-?: Join<K, Leaves<T[K], Prev[D]>> }[keyof T] : "";

src/autocomplete/QueryMatcher.ts

@@ -20,10 +20,11 @@ import { at, uniq } from 'lodash';
 import { removeHiddenChars } from "matrix-js-sdk/src/utils";
 
 import { TimelineRenderingType } from '../contexts/RoomContext';
+import { Leaves } from "../@types/common";
 
 interface IOptions<T extends {}> {
-    keys: Array<string | keyof T>;
-    funcs?: Array<(T) => string | string[]>;
+    keys: Array<Leaves<T>>;
+    funcs?: Array<(o: T) => string | string[]>;
     shouldMatchWordsOnly?: boolean;
     // whether to apply unhomoglyph and strip diacritics to fuzz up the search. Defaults to true
     fuzzy?: boolean;